Blood Pressure and Heart Health: Resveratrol is a very important flavonoid antioxidant that directly affects the functioning of certain mechanisms in blood vessels, primarily making them less prone to damage by angiotensin, which can cause blood vessel constriction. In fact, resveratrol increases the production of nitric oxide, which is a vasodilator, meaning that it relaxes blood vessels and reduces chances of blood clot formation and subsequent heart issues like strokes or heart attacks. Resveratrol is found in many dark-skinned berries like mulberries, including most grapes, which is why this beneficial antioxidant is also found in many wines.